Automotive collision avoidance sensor system

ABSTRACT

In an automotive collision avoidance sensor system installed at both the fore and aft of a vehicle, there is provided an output lens, an input lens, and a transmit laser. The transmit laser is adapted to transmit a pulsed beam through the output lens to impact roadway, surrounding vehicles or objects fore, aft, port and starboard of the vehicle, with return signals from the roadway, surrounding vehicles or objects reflecting off the input lens. A sensor of the system adapted collects the return signals from the input lens to convert them into output voltages and signals, and has a data processor configured to analyze the output voltages and signals so as to calculate real-time 3-dimensional situation awareness measurements and safety metrics which are constantly measured and updated to prevent possible collision.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §120 to U.S.patent application Ser. No. 14/218,607, filed Mar. 18, 2014 to Aina etal. (pending/allowed) which is herein incorporated by reference in itsentirety.

BACKGROUND

Field

The example embodiments in general are directed to an automotivecollision avoidance sensor system.

Related Art

Lasers or other forms of coherent electromagnetic radiation (ER) todayhave numerous applications, such as applications for marking and guidingmunitions, vehicles, determining distance (ranging), navigating,surveying, remote sensing, highlighting an object and so on. Inresponse, laser warning receiver (LWR) systems have become important todetect and process laser emissions. Typically, a LWR is a passive systemthat detects incoming laser emissions and processes the incoming laseremissions for various parameters, such as range of the origin or sourceof the laser emissions to the LWR system, angle of arrival of the laseremissions, spectral content, etc. For example, it is common for militaryvehicles, such as planes, helicopters, ships, etc., to be equipped witha LWR system. LWR systems may also be used in civilian or commercialsettings, such as for vehicle safety, mass transit, etc.

Currently, the known LWR's are limited in sensitivity, range, spectralcoverage (e.g., range of wavelengths detectible by the LWR system),angular coverage, operating temperature, resolution, etc. Moreover,current LWR devices are large and/or bulky and consume large amounts ofpower. This makes the known LWR systems unsuitable for many applicationsin which they would otherwise be useful. Furthermore, the known LWR'sare prone to false alarms due to ambient light and/or other sources ofoptical emissions, which are common in the environment.

Applicant described a solution to the above limitations in theirco-pending '607 application, presenting an electromagnetic or laserwarning sensor of an optical detection system and system thereof. Ingeneral, the system includes a Fresnel lens coupled to an array ofphotodetectors having a pixel pitch which enabled an angular coverage ofup to 360°.

In operation, the Fresnel lens collects incident optical signals andfocuses the same onto the array, where the optical signals intoelectrical outputs analyzed by the optical detection system todetermine, for each optical signal, an incident angle of arrival ofthereof, and a range of a source of the optical signal to the sensorthat is determined from the calculated angle of arrival. The electricaloutputs were further analyzed to minimize a false alarm rate bydiscriminating each optical signal spectrally to calculate a wavelengththereof, so as to distinguish whether an incident optical signal is froma narrowband laser source operating at a single wavelength or from abroadband light source operating at a continuum of wavelengths.

Applicant has discovered that their sensor technology, with slightvariations, is applicable to automotive collision avoidancetechnologies, for both driver and driverless cars. Currently, it hasbeen observed that smart/intelligent cars (such as those of UBER® orGOOGLE®) are employing LiDAR. These are cumbersome and expensive($65,000) systems, typically sitting 4 feet above the driver line ofsight, and utilizing several rotating lenses in an effort to build apicture of the 3D environment around the car. The sensitivity of thesesensors is also poor, particularly degrading in poor weather/visibilityconditions (fog, snow, rain, etc.). Moreover, these current LiDARsystems are limiting in terms of their actual capability, and can onlysee a swath or narrow beam angle at a time. So instead of a complete 360degree view, a series of cylindrical views are fed into a computationengine, thus it is a very computation-intensive system. Therefore, thesesystem cannot provide the 3D picture at every instant as can the humanbrain, being limited by the frame rate (typically 10-60 Hz) which is waytoo slow a reaction/refresh time.

What is needed is a collision avoidance sensor system providing a lowercost, lower power and less computationally intensive solution,particularly one which is more sensitive as well as requiring less powerboth in normal and obscured conditions.

SUMMARY

An example embodiment is directed to an automotive collision avoidancesensor system installed at both the fore and aft of a vehicle, whichincludes an output lens, an input lens, and a transmit laser. Thetransmit laser is adapted to transmit a pulsed beam through the outputlens to impact roadway, surrounding vehicles or objects fore, aft, portand starboard of the vehicle, with return signals from the roadway,surrounding vehicles or objects reflecting off the input lens. A sensorof the system adapted collects the return signals from the input lens toconvert them into output voltages and signals, and has a data processorconfigured to analyze the output voltages and signals so as to calculatereal-time 3-dimensional situation awareness measurements and safetymetrics which are constantly measured and updated to prevent possiblecollision.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will become more fully understood from the detaileddescription given herein below and the accompanying drawings, whereinlike elements are represented by like reference numerals, which aregiven by way of illustration only and thus are not limitative of theexample embodiments herein.

FIG. 1 shows a simplified block diagram of Applicants laser warningreceiver (LWR) system of their '607 application.

FIG. 2 shows a more detailed block diagram as shown in FIG. 1.

FIG. 3 shows implementation of the block diagram of FIG. 2 in moredetail.

FIG. 4 shows an alternative circuit diagram of system 100 fromApplicant's '607 application.

FIG. 5 shows an exemplary resistive load circuit interface that may beemployed in some embodiments.

FIG. 6 shows a more detailed block diagram of the sensor.

FIG. 7 is directed to a 2D optics and detector array.

FIG. 8 shows an image of an exemplary 2D detector array.

FIG. 9 conceptually illustrates how laser emissions and its angle ofarrival are captured by the 2D detector array in the sensor.

FIG. 10 illustrates an algorithm for angular determination of an opticalsignal, such as a laser, using the 2D array in a sensor.

FIG. 11 shows one example of how data from the detector 106 may beprocessed to determine angular information of laser emissions.

FIG. 12 shows exemplary 1D detector arrays.

FIG. 13 conceptually illustrates how laser emissions are distinguishedfrom other types of optical information by the 1D detector array.

FIG. 14 is a general process flow for explaining the methodology fordetecting threats.

FIG. 15 is a more detailed process flow.

FIG. 16 is a process flow for laser emission detection.

FIG. 17 illustrates how the system sets a detection threshold.

FIG. 18 is a picture of an automotive collision avoidance sensor systemmounted on an automobile, according to the example embodiments.

FIG. 19 is a block diagram of the sensor system of FIG. 18.

FIG. 20 is a general electro-optical flow diagram to explainfunctionality of the sensor system.

DETAILED DESCRIPTION

Before delving into Applicant's novel automotive collision avoidancesystem, Applicants provides the background of their electromagnetic orlaser warning sensor as described in the co-pending '607 application. Inthe following description, certain specific details are set forth inorder to provide a thorough understanding of various example embodimentsof the disclosure. However, one skilled in the art will understand thatthe disclosure may be practiced without these specific details. In otherinstances, well-known structures associated with manufacturingtechniques have not been described in detail to avoid unnecessarilyobscuring the descriptions of the example embodiments of the presentdisclosure.

Unless the context requires otherwise, throughout the specification andclaims that follow, the word “comprise” and variations thereof, such as“comprises” and “comprising,” are to be construed in an open, inclusivesense, that is, as “including, but not limited to.”

Reference throughout this specification to “one example embodiment” or“an embodiment” means that a particular feature, structure orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearances of the phrases “in oneexample embodiment” or “in an embodiment” in various places throughoutthis specification are not necessarily all referring to the sameembodiment. Further, the particular features, structures orcharacteristics may be combined in any suitable manner in one or moreexample embodiments.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include plural referents unless the contentclearly dictates otherwise. The term “or” is generally employed in itssense including “and/or” unless the content clearly dictates otherwise.

As used in the specification and appended claims, the terms“correspond,” “corresponds,” and “corresponding” are intended todescribe a ratio of or a similarity between referenced objects. The useof “correspond” or one of its forms should not be construed to mean theexact shape or size. In the drawings, identical reference numbersidentify similar elements or acts. The size and relative positions ofelements in the drawings are not necessarily drawn to scale.

In Applicant's co-pending '607 application, which forms the basis forthis new subject matter, there is described a laser sensing system thathas high angular resolution and is sensitive to a low laser powers. Thesensing system is sensitive to a wide range of wavelengths, has up to a360° angular coverage at the aperture of the system, and has highdiscrimination and angular resolution (e.g., the measure (in degrees orradians) of the system's ability to detect small details of the incidentoptical signal with high accuracy). In one embodiment, the laser sensingsystem has a near-zero false alarm rate ((FAR), e.g., the raterepresenting the time between false alarms with the system activated),nanowatt/cm2 optical sensitivity, and high detection probability. Inaddition, the system has spectral discrimination (e.g., the ability todetermine the actual wavelength(s) of an optical signal incoming orincident to the system so as to discriminate a laser emission(narrowband and at a single wavelength) from a light emission (broadbandsignal with a spread of wavelengths) and or high angular resolution.

The following FIGS. 1-17 of Applicant's co-pending '607 application areprovided as a backdrop to understanding Applicants' collision avoidancesystem and method. FIG. 1 shows a simplified block diagram ofApplicant's laser warning receiver (LWR) system of their '607application. In general, the system 100 may be deployed in numeroustypes of application. For example, the system 100 may be used as a laserwarning receiver (LWR) system to detect a laser emission, e.g., from athreat or hostile source. LWR systems may be used in various settings,such as military operations, air travel, law enforcement, security, etc.Alternatively, the system 100 may be used in a civilian setting, such asfor an automobile or train that uses laser to detect proximity to othervehicles or objects. For purposes of illustration, examples of thesystem 100 used as a LWR is provided in the present description.However, one skilled in the art will recognize how the embodiments maybe implemented in a variety of settings.

TABLE 1 shows some exemplary performance specifications that may beachieved by Applicants LWR system.

TABLE 1 PERFORMANCE SPECS Spec Description Spectral Coverage 450 nm to1550 nm Sensitivity 10 nW/cm² False Alarm Rate <1 per 1000 hours AngularCoverage 100° Angular Resolution  1-2° Size, Power 3.2 × 3.2 × 2 in (81× 81 × 51 mm), 3 W Operating Temperature 0° C. to 60° C.

As shown, the 100 may comprise a sensor 102, which further comprisesoptics 104 and a detector 106, a sensor interface 108, a processor 110,and an optional output device 112. The sensor 102 receives light andlaser emissions and provides an output to indicate various parametersabout the light and laser emissions. As noted, the sensor may compriseoptics 104 and a detector 106.

The optics 104 are responsible for collecting the light and (if present)laser emissions and focusing the light onto the detector 106. In someembodiments, the optics 104 may be an optical package that comprises alens and/or other types of ports. In one example, the optics 104 may bean optical package that comprises comprise a Fresnel lens and an opticalgrating. In another example, optics 104 may be an optical package thatcomprises a doublet Fresnel lens for 2D angle resolving detection (EFL2.5 mm, FOV)>100° and a transmission grating and cylindrical lens (FL 5mm, FOV)>100° focused on a one-dimensional linear array (1D array) foroptical false alarm rejection.

The detector 106 is responsible for converting the light energy andreceived laser emissions into an electrical output. In one embodiment,the detector 106 may comprise an array of avalanche photodiodes (APDs)that are sensitive to various forms of light and laser emissions.Detector 106 may comprise multiple arrays of detectors to discriminatelaser emissions and minimize/avoid false alarms. For example, thedetector 106 may comprise a two dimensional (2D) array of APDs that formindividual pixels and a one dimensional array (1D) array of APDs.

The angular coverage at the aperture of the 2D array depends directly onthe pixel pitch, the number of pixels of the APD arrays and the opticalconfiguration of the sensor 102. In an embodiment, the aperture ofdetector 106 in sensor 102 of system 100 has up to a 360° angularcoverage. In this embodiment, the APD array layout may range from about50-um pixel diameter and a pitch that ranges from about 150-um to 210-umpitch.

The sensor interface 108 is responsible for acquiring the signals fromthe detector 106 and converting them into useful output voltages andsignals for analysis by the processor. In some embodiments, the sensorinterface 108 comprises a readout integrated circuit (ROIC).

The processor 110 is responsible for analyzing the output of the sensorinterface 108 and determining various parameters, such as angle ofarrival of laser emissions, spectral content, range to source of laseremissions, etc. In one embodiment, processor 110 comprises a fieldprogrammable array (FPGA) module to process the detector data. Forexample, the processor 110 may be implemented based on an Opal KellyXEM6010 Spartan-6 FPGA module. Alternatively, the processor 110 may be amicroprocessor, such as a Rabbit Core RCM3400 microprocessor. Oneskilled in the art will recognize that various types of processors maybe used in the embodiments.

The processor 110 may execute various algorithms and processes usingexecutable program code and software. Data processing algorithms fordetection and false alarm rejection and angle are further describedbelow.

The processor 110 may also execute a software interface through acommunications interface, such as RS-485 connector, a wireless network,etc. In some embodiments, processor 110 may execute software fordetection and alarm declaration with or without real time data storage,for example, onto a storage card or other medium. The processor 110 mayalso be provided with GPS connectivity.

The output device 112 is an optional device of system 100 so that a usercan interface with the system 100. For example, the output device 112may be a speaker or display, a computer, a laptop, or other form of userinterface device. The output device 112 may also comprise an interfaceto other computing systems, such as one or more communications ports oran application programming interface.

In one embodiment, the output device 112 is adaptable to varioussystems. For example, the output device 112 may employ one or morestandard communications protocols, such as RS-485, as an outputinterface. The output device 112 may thus provide information about thethreat and periodic system status updates.

FIG. 2 shows a more detailed block diagram and FIG. 3 showsimplementation of the block diagram of FIG. 2. The electrical powersystem board (EPS) regulates power to all components in the system. Theprocessor interface board (PIB) implements the digital control logic andsignal processing. The motherboard is a single board with ground planeto hold detectors and analog to digital conversion chips.

In FIG. 2, the detector board contains the APD array for detector 106and sensor interface 106 as a ROIC, a motherboard containing thedetector board and the processing and interface electronics. As alsoshown, the power components, such as bias regulators and power drivers,are located on a separate board, for example, to reduce noise in system100. As shown, the motherboard includes the detector board, athermoelectric cooler (TEC), a TEC driver and a thermistor fortemperature stabilization of the LWR.

In one embodiment, the control and data processing components may employan FPGA. For example, the Spartan-6 FPGA may be used to control theonboard chips (MUX, ADC, DAC, ROIC, RS485) and for processing thedetector outputs and running the detection algorithms. Alternatively, amicroprocessor may be used for onboard chip control and signalprocessing.

FIG. 4 shows an alternative circuit diagram of its system 100 thatemploys resistive load circuit interfaces that may be used to break theconnection of an APD pixel if that pixel becomes defective. FIG. 5 showsan exemplary resistive load circuit interface that may be employed insome embodiments.

Resistors may be used in the sensor interface 108 to convert thephotocurrent from the detector 104 into output voltages. This alternateapproach may have better noise performance and speed. In thisembodiment, all APD outputs from the detector 106 feed through aresistive load circuit (shown in FIG. 3) to convert optical current tovoltage. Analog multiplexors may be used to switch between the detectoroutputs and connect to the ADCs on the motherboard.

FIG. 6 shows a more detailed block diagram of the sensor. In thisembodiment, the sensor 102 comprises an ultrasensitive wavelengthdispersive photoreceiver array operating in the 450-1550 nm wavelengthrange. In some embodiments, the array(s) of sensor 102 can operate in awavelength range between about 200 nm to 3000 nm. The photoreceiverarray consists of specialized optics (2D optics 104A and 1D optics 104B)and the APD array (see 2D detector array 106A and linear 1D detectorarray 106B), and the sensor electrical interface 108 (not shown) is aread out integrated circuit (ROIC).

Angle of arrival detection is accomplished by using a Fresnel lens inoptics 104A to focus incoming signals onto a pixel on an 8 by 8 APDdetector array 106A. The angular discrimination can be determined by thepixel detecting the focused optical signal or the algorithms can be usedto determine the angle of arrival.

Spectral discrimination and false alarm rejection is accomplished byusing a transmission grating as part of 1D optics 104B and a cylindricallens over a linear 1 by 16 APD detector array 106B (“1D detector array106B”) and is used by the algorithms for false alarm rejection.

FIG. 7 is directed to a 2D optics and detector array, showing an imageof exemplary optics that may be employed in the sensor 102. As shown,the optics 104 may comprise a Fresnel lens as optics 104A and atransmission grating as optics 104B. FIG. 8 shows an image of anexemplary 2D detector array.

To understand the determination of angle of arrival of a laser emission,FIG. 9 conceptually illustrates how laser emissions and its angle ofarrival are captured by the 2D detector array 106A of sensor 102. Athreat laser or optical signal is incident on the LWR system 100 or iscaused to be incident by atmospheric scattering on the aperture of thedetector array 106A. The incident optical signal is transmitted throughthe Fresnel lens of 2D optics 104A on to the detector array 106A.Angular information is embedded in the detected optical and photocurrentsignal. An angular discrimination algorithm is then used to determinethe angle of arrival.

The angle of arrival can be determined from the relative intensity ofall the pixels in the detector array 106A. The technique is based on theknown non-coherent Fresnel finding technique. In particular, the Fresnellens located at the aperture of detector array 106A causes thetransmittance of the radiation to vary continuously as a function of theincident angle. The intensity at each pixel in the detector array 106Ais thus a function of the angle of each pixel relative to the emissionsource, and the range and the resolution is a function of the relativeintensity distribution over the image formed by the pixels in thedetector array 106A.

The measured relative intensities at each pixel provide enoughinformation for range determine using algorithms and by electronicsignal processing of the pixel photocurrent data.

The angle of arrival (Theta) can be calculated using the angle dependentFresnel transmission curves, which can be correlated to the photocurrentsignals I generated by each pixel of the detector array using thefollowing equations:

$\theta_{1} = {{{f\lbrack \frac{I_{1}}{I_{1} + I_{2}} \rbrack}\theta_{2}} = {{{f\lbrack \frac{I_{2}}{I_{1} + I_{2}} \rbrack}\theta} = {f\lbrack \frac{I_{1} - I_{2}}{I_{1} + I_{2}} \rbrack}}}$

In addition, the range of the origin or source of the laser to system100 may be calculated based on the following equation:

$R = {{\frac{d}{2\; \cos \; \theta_{2}}\lbrack \frac{{\sin^{2}\theta_{2}} - {\sin^{2}\theta_{1}}}{\sin^{2}( {\theta_{2} - {\sin^{2}\theta_{1}}} )} \rbrack} - 1}$

Angular Determination Algorithm.

Various algorithms may be used for determining the incident angle of anoptical signal, such as a laser emission. These non-linear equations canbe solved using non-linear equation solvers that may be programmed intoFPGAs or as a microprocessor firmware, or software as part of processor110. In general, the angular recognition algorithm comprises: measuringphotocurrents of pixels received by the sensor; calculating photocurrentratios; solving the nonlinear equations to determine an angle of arrivalof the optical signal; and using the angle of arrival to determine adistance of the optical signal.

One example is described with reference to determining the angle anddistance of an optical signal, such as a laser. As shown in FIG. 10, anLWR optical configuration for system 100 is illustrated. In FIG. 10, thedots represent the laser at different angular positions relative to thepixels, which are numbered p1 to p6, for example. The distance betweenthe laser and the LWR at any arbitrary angular position, r_(i), and thephotocurrent at each pixel, i_(phi), can be expressed by the classicalrange equation and the Fresnel equation as follow:

$\begin{matrix}{r_{i} = {{\frac{a}{2}\lbrack \frac{\sin \; \theta_{i}}{\sin ( {\theta - \theta_{i}} )} \rbrack} = {\sqrt{\frac{G}{i_{phi}}}e^{{- \beta}\; r_{i}}}}} & 1 \\{r_{i} = {{\frac{a}{2\; \cos \; \theta_{i + 1}}\lbrack \frac{{\sin^{2}\theta_{i + 1}} - {\sin^{2}\theta_{i}}}{\sin^{2}( {\theta_{i + 1} - {\sin^{2}\theta_{i}}} )} \rbrack} - 1}} & 2 \\{i_{phi} = {{\frac{4\; G}{d^{2}}\lbrack \frac{\sin^{2}( {\theta - \theta_{i}} )}{\sin^{2}\theta} \rbrack}e^{{- 2}\beta \; r_{i}}}} & 3\end{matrix}$

In the above, θ_(i) is the angle of incidence on pixel p_(i), θ is theangle subtended between the source and the midpoint between pixels p_(i)and p_(i+1). G is the constant in the range equation which accounts forthe detector performance and other physical constants, d is the spacingbetween the pixels and b is the optical attenuation coefficient.

The intensity ratio at each pixel can then be expressed as:

$\begin{matrix}{\frac{i_{phi}}{i_{{ph}\; 1} + i_{{ph}\; 2} + \ldots + i_{phi}} = \frac{\lbrack \frac{\sin^{2}( {\theta - \theta_{i}} )}{\sin^{2}\theta} \rbrack}{\lbrack \frac{\sin^{2}( {\theta - \theta_{1}} )}{\sin^{2}\theta} \rbrack + \lbrack \frac{\sin^{2}( {\theta_{2} - \theta} )}{\sin^{2}\theta_{2}} \rbrack + \ldots + \lbrack \frac{\sin^{2}( {\theta_{i} - \theta} )}{\sin^{2}\theta_{i}} \rbrack}} & 4\end{matrix}$

Equation 4 can be used to generate i non-linear equations with ivariables and the intensity ratios are based on the measuredphotocurrent data at each pixel. Any other type of non-linear equationscan be formulated based on any functions or transform of thephotocurrent data. The most obvious of these is the intensity ratio,which has the advantage of normalizing the data to eliminate systematicanomalies.

FIG. 11 shows one example of how data from the detector 106 may beprocessed to determine angular information of laser emissions inaccordance with the principles of the present invention. As shown, theprocessor 110 may comprise an angular discrimination processor, whichinterprets the embedded angular information provided by the detector 106104. In this embodiment, the processor 110 employs a database regressionanalysis to then determine the angle of arrival, for example, using alookup table described below. The processor 110 may execute variousroutines and subroutines based on program code, such as VHDL, and C++ toperform the angle of arrival determination and range determinationalgorithms of the equations described above.

False Alarm Rejection. FIG. 12 shows exemplary 1D detector arrays thatmay be used in some embodiments. In one embodiment, the 1D detectorarray 106B may comprise a linear 1×16 array of APDs. The 1×16 lineararrays may be designed to detect and discriminate optical signalspectrally dispersed by transmission gratings for wavelengthdiscrimination and false alarm rejection. A resistive load or an ROICmay be used to convert the optical currents of the 1×16 linear array tovoltages and to send the 16 pixel data to the sensor interface 108 inparallel.

FIG. 13 conceptually illustrates how laser emissions are distinguishedfrom other types of optical information by the 1D detector array 106B ofthe embodiments. In particular, the 1D detector array 106B may be usedto avoid/minimize false alarms. The false alarm rejection is based onspectral discrimination, pulse repetition frequency (PRF), pulse-widthand threshold

As shown, the 1D detector array 106B receives an optical signal from 1Doptics 104B, which may be configured as a transmission grating andcylindrical lens focused. As shown, the incoming threat optical signalpasses through the grating, which disperses the photons spatiallydepending on their wavelength. Lasers operating at a single wavelengthwill only illuminate a small area of the 1D detector array 106B and willtherefore be incident at a predetermined pixel depending on the opticaldesign. Broadband light sources, however, have a continuum ofwavelengths and thus will be split into individual wavelengths andilluminate many pixels. Using the pixel distribution of photocurrent onthe linear array, the LWR electronics of system 100 can determine if theoptical signal is coming from a narrowband source and at whatwavelength.

The normalization of the output signals allows the range measurement tobe independent of the signal level from the target. Therefore, bymeasuring the photocurrents of the detector array pixels the angles canbe calculated.

Exemplary Software Process Flows. FIG. 14 shows an exemplary generalprocess flow for the software behind Applicant's system in the '607application. FIG. 15 shows another software process flow, and FIG. 16shows a software process flow for detection of laser emissions. Theseprocess flows may be implemented as software using known executableprogram code language, such as VHDL, C, C++. Those skilled in the artwill recognize that any programming language and program code using anynumber of subroutines, libraries, etc. may be employed in theembodiments. In another embodiment, the spectral signature of theoptical signal may be determined. The spectral discrimination featuremay be implemented using filters provided at each of the pixels. Forexample, semiconducting optical amplifiers, such as fabry-perot filters,may be implemented. Any type of filter may be implemented using knowntechniques.

Alternatively, spectral discrimination may be accomplished using agrating to spatially disperse the optical signal onto an array of pixelsdesigned to correspond to different wavelengths. These spectraldiscrimination features enable false alarm rejection, threatidentification, classification, as well as spectral binning to reducefalse alarms and enable the capability for day/night operation.

Detection Threshold. FIG. 17 illustrates how the system 100 sets adetection threshold. The detection threshold analysis is based onconcepts and formulas used to characterize bit error rate (BER) incommunications, which is equivalent to the false alarm rate (FAR) indetection theory. The FAR is related to the sensitivity, which may beexpressed by the following equations:

S _(min) =Q*NEP

FAR=1/2[1−erf(Q/√2)]˜1/√(2p)[exp((−Q ²/2))/Q]   3.2.2

FAR˜NEP/√(2p)[exp((−(S _(min)/NEP)²/2))/S _(min),]   3.2.3

In the above, NEP is the noise equivalent power at which thesignal-to-noise ratio (SNR) is 1, Q is the error or false alarm factorwhich is related to FAR by an error function for generalized noise or aGaussian function for Gaussian noise. While NEP is the minimum noisepower (sensitivity) at SNR=1, S_(min) is the sensitivity at an SNRdesigned to produce a particular FAR. These equations were used toestimate the trade-off between FAR and sensitivity. For these estimates,the threshold may be set to yield a probability of detection close to100%.

Applicant's LWR sensor system 100 having been described in detail, theexample embodiments are now directed to an automotive collisionavoidance system and method that can be fabricated at lower cost, useslower power in both normal and obscured conditions, is much lesscomputationally intensive, and much more sensitive to thereby provide360 degree coverage with greater accuracy then current solutions.

Referring to FIG. 18, in general, there is shown an automotive collisionavoidance sensor system 200 (“sensor system 200”) for that has a LWRsensor therein (similar to as described in FIGS. 1-17) configured todetect the smallest quanta of light from reflecting surfaces of cars,moving objects and the like. Although shown in FIG. 18 in an applicationfor automotive collision avoidance, this example sensor system 200 isequally applicable to robotics, obstacle warning systems, lane changeassist systems, autonomous vehicle systems, traffic cop warning devicesfor automobile drivers, and the like.

In an example, the sensor system 200 is mounted in both the fore and aftof the vehicle (generally along the line of sight of the driver in thefront grill and rear bumper, as an example), and is capable of detectingscattered laser signals from the nearby vehicles Similar to LWR systemin FIGS. 1-17 sensor system 200 has integral signal processingalgorithms and software to determine the distance, angle, speed andbearing of nearby vehicles. If a collision event is imminent, the sensorsystem 200 alerts the driver or through a commend signal to installedvehicle safety software applies corrective actions such as brakingand/or adjustment of steering to avoid the accident.

FIG. 19 is a block diagram of the sensor system 200. In general, thesensor system includes optics 204 (which may include both an input lensfor reception and an output lens for transmission), a collisionavoidance laser warning sensor 210 (hereafter “CA sensor 210”), atransmit laser 220 and an optional local oscillator (LO) laser 230 forcoherent sensing and greater sensitivity. The CA sensor 210 has aminimum detectable intensity of 10 nanowatts per square centimeter andis essentially the LWR sensor of the co-pending '607 application, but asit is employed with a transmitting laser, it can be referred to as anactive laser sensor. CA sensor 210 and the lasers 220, 230 are affixedto a printed circuit board 202 which is electrically connected viaconnector 203 to vehicle power and other on-board electronics.

Optics 204 may be an optical package that comprises one Fresnel lens forthe input and another for the output lens of optics 204, with or withoutan optical grating. In another example, optics 204 may be an opticalpackage that comprises a doublet Fresnel lens (I/O lenses) and also for2D angle resolving detection (EFL 2.5 mm, FOV)>100° and a transmissiongrating and cylindrical lens (FL 5 mm, FOV)>100° focused on aone-dimensional linear array (1D array) for optical false alarmrejection. Optics 204 could be a combination lens setup with transmitterlens on the output side and Fresnel on the receive/input side.

As previously described with the LWR sensor 102, CA sensor 210 isadapted to collect the incident optical signal, and includes a detectorarray of photodetectors (as was described for detector 106 in FIGS.1-17) having a pixel pitch from about 150 μm to 210 μm enabling anangular coverage of up to 360°. The detector array converts thecollected incident optical signal(s) into a photocurrent for output fromthe CA sensor 210, via a sensor interface (such as a ROIC) coupled tothe sensor to convert the photocurrent into output voltages and signalsfor analysis by an enhanced data processor coupled to the sensorinterface. The basic block diagram of FIG. 1 is thus applicable here aswell, although the processor in this embodiment is an enhanced dataprocessor that calculates ranging information (distance, azimuth, andelevation), 3D rendering, issues warning and alarms and performsautomated collision avoidance in driverless mode).

In one specific configuration, and similar to as specified for LWR 102above, the optics 204 may be embodied as a doublet Fresnel lens, and thedetector array may be a two dimensional (2D) detector array of avalanchephotodiodes (APDs) coupled to the Fresnel lens to convert the opticalsignal into a photocurrent. Output voltages and signals converted fromthe 2D detector array photocurrent by the sensor interface are employedwith Fresnel equations in algorithms iterated by the processor todetermine the range, azimuth, elevation). In an example, the 2D detectorarray may have a breakdown voltage of 35 volts, a dark current of lessthan 100 nA, and an optical gain between 10-15 A/W.

Further, and similar to as specified for LWR 102 above, here the CAsensor 210 may further includes a transmission grating with cylindricallens attached thereto, and a linear (1D) detector array coupled to thegrating and to the cylindrical lens, the incident optical signal passingthrough the grating, which disperses photons thereof spatially dependingon wavelength, the photons collected by the cylindrical lens anddirected to the 1D detector array for conversion into photocurrents, theoutput voltages and signals converted therefrom by the sensor interfaceanalyzed spectrally by the processor

FIG. 20 is a general electro-optical flow diagram to explainfunctionality of the sensor system 200 in some more detail. The lasertransmitter 220 in an example may be a 1.55-um DFB laser with less than1 Watt output, either as a pulsed laser or CW laser modulated to form0.01-1-microsecond pulses. The transmit beam is then split to form theoutput beam (P_(T)) and the local oscillator beam (LO). The returnsignal from the roadway, surrounding vehicles or objects, (P_(r)) ismixed with the LO signal to generate the IF signal which is thenreceived by the CA sensor 210 for processing and analysis via its sensorinterface and data processor. In a different embodiment, the returnsignal (P_(r)) is not mixed with the LO, but is directly detected by theCA sensor 210. The input/output lenses for optics 204 could either be anintegral lens such as a Fresnel, or two separate lenses as describedabove.

Sensor system 200 is designed to provide 3D situation awareness. Namely,the CA sensor 210 with its associated data processor is adapted todetermine each of the range R, azimuth angle θ_(az) and elevation angleθ_(ele) of vehicle surroundings. In other words, information as to theproximity of objects fore, aft, starboard and port are constantlymeasured and updated. CA sensor 210 with its associated data processorthen builds a point cloud of vehicle surroundings from the R, θ_(az) andθ_(ele) data, and then builds a 3D model of vehicle surroundings fromthe point clouds. This 3D model will be similar to, but more precisethan what a human driver would see if he/she had 180° field-of-view(FOV). The CA sensor 210 then constructs a safe zone (such as a safebreaking distance zone) in the 3D model and generates alarms or takesevasive actions for any intrusion into the safe zone.

The sensor system 200 is foreseen in various operational scenarios. Inone example, system 200 may include a vehicle cutting-in warning/brakingsystem command setup; in another, a vehicle ahead sudden brakingwarning/braking system command setup. Sensor system 200 may also providea side-swipe avoidance system function to the driver or car.

The sensor system 200 employs an active CA laser sensor 210, operatingin wavelengths of near-uv, or blue (350-450 nm) to penetrate fog andenhance sensitivity in obscured conditions. As the transmit laser 220emits a pulsed beam, a high frame rate is not needed.

Accordingly, the automotive collision avoidance sensor system 200described herein provides 3-dimensional situation awarenessmeasurements, namely real-time distance, azimuth and elevation angles ofobjects. Sensor system 200 offers automobiles the same 3D situationawareness capabilities as humans. The proximity of objects fore, aft,starboard & port are constantly measured and updated. Safe breakingdistance may be constantly measured and updated, and an imminentcollision warning may be issued for proximity less than the safebreaking distance, or outside the safe zone.

The example embodiments having been described, it is apparent that suchhave many varied applications. For example, the example embodiments maybe applicable but not limited to connection to various devices,structures and articles.

The present invention, in its various embodiments, configurations, andaspects, includes components, systems and/or apparatuses substantiallyas depicted and described herein, including various embodiments,sub-combinations, and subsets thereof. Those of skill in the art willunderstand how to make and use the present invention after understandingthe present disclosure. The present invention, in its variousembodiments, configurations, and aspects, includes providing devices inthe absence of items not depicted and/or described herein or in variousembodiments, configurations, or aspects hereof, including in the absenceof such items as may have been used in previous devices, e.g., forimproving performance, achieving ease and\or reducing cost ofimplementation.

The foregoing discussion of the invention has been presented forpurposes of illustration and description. The foregoing is not intendedto limit the invention to the form or forms disclosed herein. In theforegoing Detailed Description for example, various features of theinvention are grouped together in one or more embodiments,configurations, or aspects for the purpose of streamlining thedisclosure. The features of the embodiments, configurations, or aspectsof the invention may be combined in alternate embodiments,configurations, or aspects other than those discussed above. This methodof disclosure is not to be interpreted as reflecting an intention thatthe claimed invention requires more features than are expressly recitedin each claim. Rather, as the following claims reflect, inventiveaspects lie in less than all features of a single foregoing disclosedembodiment, configuration, or aspect. Thus, the following claims arehereby incorporated into this Detailed Description, with each claimstanding on its own as a separate preferred embodiment of the invention.

Moreover, though the description of the invention has includeddescription of one or more embodiments, configurations, or aspects andcertain variations and modifications, other variations, combinations,and modifications are within the scope of the invention, e.g., as may bewithin the skill and knowledge of those in the art, after understandingthe present disclosure. It is intended to obtain rights which includealternative embodiments, configurations, or aspects to the extentpermitted, including alternate, interchangeable and/or equivalentstructures to those claimed, whether or not such alternate,interchangeable and/or equivalent structures disclosed herein, andwithout intending to publicly dedicate any patentable subject matter.

I claim:
 1. An automotive collision avoidance sensor system installed atboth the fore and aft of a vehicle, comprising: an output lens and aninput lens, a transmit laser adapted to transmit a pulsed beam throughthe output lens to impact roadway, surrounding vehicles or objects fore,aft, port and starboard of the vehicle, with return signals from theroadway, surrounding vehicles or objects reflecting off the input lens,and a sensor adapted to collect the return signals from the input lensto convert them into output voltages and signals, the sensor including adata processor configured to analyze the output voltages and signals soas to calculate real-time 3-dimensional situation awareness measurementsand safety metrics which are constantly measured and updated to preventpossible collision.
 2. The system of claim 1, wherein thethree-dimensional situation awareness measurements are real-timedistance, azimuth and elevation angles of the objects.
 3. The system ofclaim 1, wherein the constantly measured and updated safety metricsinclude a safe breaking distance or safe zone calculation.
 4. The systemof claim 1, wherein the sensor includes a detector array ofphotodetectors adapted to convert the collected return signals into aphotocurrent having a pixel pitch from about 150 μm to 210 μm enablingan angular coverage of up to
 360. 5. The system of claim 1, furthercomprising: a local oscillator (LO) laser for coherent sensing andgreater sensitivity, the beam from the LO laser mixing with the returnsignals to form an IF signal collected by the sensor.
 6. The system ofclaim 1, wherein the transmit laser has less than 1 Watt output and itsbeam modulated to form 0.01-1-microsecond pulses.
 7. The system of claim1, wherein the sensor further includes: a two dimensional (2D) detectorarray of avalanche photodiodes (APDs) which are coupled to the inputlens to convert the return signals into a photocurrent, the 2D detectorarray having a breakdown voltage of 35 volts, a dark current of lessthan 100 nA, and an optical gain between 10-15 A/W.
 8. The system ofclaim 1, wherein the sensor has a minimum detectable intensity of 10nanowatts per square centimeter.
 9. The system of claim 1, wherein thesensor operates in wavelengths of near-uv or blue (350-450 nm) topenetrate fog and enhance sensitivity in obscured conditions.